GPU passthrough poor performance - how to verify?

[jnewman33]

Hi all,

I am a hobbyist that has been using Proxmox for several years. Currently I am on 7.2-15 on a Supermicro 5028D-TN4T. This system has a VisionTek Radeon 7750 card installed. In the last month I became interested in passing through this card to a Win10 VM. This is my first experience trying to do GPU passthrough. The good news is that I seem to have the card seen properly in my VM and legacy drivers installed. Bad news is that performance seems to be no better than before the passthrough. My "measuring stick" is RDP over local network. Performance is no better than with virtualized GPU.

Hoping for some information as how to quantify performance and/or validate proper passthrough.

Thanks,
James

 

[Dunuin]

Hi all,

I am a hobbyist that has been using Proxmox for several years. Currently I am on 7.2-15 on a Supermicro 5028D-TN4T. This system has a VisionTek Radeon 7750 card installed. In the last month I became interested in passing through this card to a Win10 VM. This is my first experience trying to do GPU passthrough. The good news is that I seem to have the card seen properly in my VM and legacy drivers installed. Bad news is that performance seems to be no better than before the passthrough. My "measuring stick" is RDP over local network. Performance is no better than with virtualized GPU.

Hoping for some information as how to quantify performance and/or validate proper passthrough.

Thanks,
James

RDP never feels snappy. You could attach a display to the GPU and see if a the physical image output is better. Or start any game that got a benchmark mode (or use something like 3dmark) and compare the average FPS with and without GPU passthrough.

 

[jnewman33]

RDP never feels snappy. You could attach a display to the GPU and see if a the physical image output is better. Or start any game that got a benchmark mode (or use something like 3dmark) and compare the average FPS with and without GPU passthrough.

Hey, thanks for the quick reply!
What I have done is play something on youtube and I am getting 20% dropped frames with and without the passthrough. I am comparing that with my experience when using RDP to my physical Win PC where there are no dropped frames. I am not sure if that is a apples to apples comparison though.

 

[leesteken]

What I have done is play something on youtube and I am getting 20% dropped frames with and without the passthrough. I am comparing that with my experience when using RDP to my physical Win PC where there are no dropped frames.

My passed through Radeon HD 7750 works fine with Youtube on Linux on a physical display. I'm not sure of the quality/performance of the AMD Windows drivers for that old GPU. Alao, can you please check with a physical display (since I expect RDP too ignore the GPU)?
Maybe boot the same VM with a Ubuntu installer LiveCD? Not to install it, but to see the performance of the GPU on Linux (optimized drivers included) on a physical display. Performance should be more than fine for Youtube and simple games, unless you have a very old CPU.

 

[Dunuin]

The 7750 is 10 years old and might not support hardware docoding of modern codecs. If playback will be better really depends on the codec used by the video you are playing. Is uses UVD 4.2, so see this table for supported codecs: https://en.wikipedia.org/wiki/Unified_Video_Decoder#Format_support
So it can't accelerate stuff like AV1, VP9, H.265 and so on.